What is behind the Pakistani Taliban’s deadly insurgency?

Security officials and rescue workers gather at the site of suicide bombing, in Peshawar, Pakistan (Zubair Khan/AP)

The Pakistani Taliban, also known as Tehreek-e-Taliban Pakistan (TTP), claimed responsibility for Monday’s suicide bombing at a mosque inside a police compound in the north-western city of Peshawar, in one of the deadliest attacks on security forces in recent months.

The bombing is likely to strain relations further between Pakistan and neighbouring Afghanistan’s Taliban rulers, who are sheltering the TTP leadership and fighters.